1. Field of the Invention
The present invention relates to a fireproof structure and installation method for water pipes used in heat exchangers in incinerators, boilers and the like which protects them in high temperature gas environments.
2. Description of the Related Art
Water pipes are installed inside of trash incinerators, boilers and the like to cool the high temperature gas environment or perform heat exchange. Those water pipes have been protected from not only the high temperature gas environment, but the abrasion from flying ash and corrosion, by the installation of fireproof tiles or fireproof castable structures around the inside of the furnace walls.
Such conventional fireproof structures, as shown in FIG. 9, have studs 14 protruding from water pipes 10 on the combustion chamber side of the water pipe wall, in other words, the side in contact with the high temperature gases. Also employed are sleeves 19 embedded inside fireproof castable 12; the foregoing studs 14 inserted into the sleeves 19 are held by the foregoing fireproof castable 12.
The foregoing fireproof castable 12 contains SiC, which exhibits high thermal conductivity and is chemically stable. The foregoing studs 14 are made of stainless steel materials, and the sleeves 19 are made of ceramic material. The sleeves 19 protect the foregoing studs 14 from corrosion by the waste gases and further serve to prevent the fireproof castable from cracking and chipping off due to studs 14.
This structural method for fireproof structures using fireproof castable materials was disclosed in Japan Patent Publication Hei 8-21688 (1996).
Also, Japan Patent Publication 2000-167816 proposed a fireproof tile using SiC and other ceramic raw materials. FIGS. 10 and 11 show a fireproof structure using the fireproof tiles disclosed in that invention.
In that structure, fins 11 that join adjacent water pipes 10 include projecting hanging members 15d. The hanging members 15d affix fireproof tiles 13 with mortar 20 on the high temperature gas side of water pipes 10 through the projecting hanging member.
As is shown in the side view, FIG. 11, the hanging members 15d comprise an L-shaped support hook. The L-shaped hooks provide support by allowing insertion of the fireproof tiles from above, which tiles are equipped with attachment holes.
However, the problem with the above described fireproof castable is that because it is of irregular dimensions, being coated or sprayed directly onto the walls of the water pipes, the durability of the resulting fireproof structure becomes unstable; after a few years, it tends to massively flake away or collapse. With regard to the fireproof structure comprised of the externally formed and manufactured fireproof tiles described above, even though the tiles themselves have excellent durability, should any of them fall off, the water pipe can be directly exposed, and be damaged by the high temperatures and corrosive gasses.
In particular, when used in the stoker-type incinerators where the outlet temperatures can reach to an extremely high 1000° C., the difference between the thermal expansion of the support members for the fireproof structures using the foregoing fireproof castables or fireproof tiles, and that of the fireproof structure, causes cracks to form where combustion gases can invade and subsequently corrode the foregoing support members. As a result, the foregoing fireproof structures are prone to separation and falling away, thereby allowing holes to form in the water piping.